Generally, a conventional display device may include a liquid crystal display (LCD), a plasma display panel (PDP) and the like.
Different from the PDP that is self-luminescent, the LCD is not self-luminescent and it requires a backlight unit as a self-luminescent.
Such a backlight unit used in the LCD may be categorized into an edge backlight unit and a direct backlight, based on location of a light source. In the edge type, light sources are disposed on right and left lateral surfaces or up and down lateral surfaces of an LCD panel. Light may be dispersed to a front surface by a light guide plate uniformly. Because of that, the edge backlight unit has good uniformity of light and it may enable the panel ultra-thin.
The direct backlight unit is used for a 20-inch-or-more display. In the direct backlight unit, light sources are disposed on a backside of a panel. Because of that, the direct backlight unit has an advantage of better luminous efficiency than the edge backlight unit and it is used for a large display requiring high brightness.
A cold cathode fluorescent lamp (CCFL) is used for the light source of the conventional edge backlight unit or the direct backlight unit.
However, an electric voltage is applied to the backlight unit using the CCFL constantly and the amount of used electricity is increased. The CCFL has a disadvantage of approximately 70% of color reproduction, compared with a cold cathode fluorescent lamp (CCFL) and another disadvantage of environmental pollution because of mercury added thereto.
To solve such disadvantages, there have been actively in progress studies on a backlight unit using a light emitting diode (LED) substituting for the CCFL.
In case of using the LED for the backlight unit, a partial on/off of LED arrays may be enabled and power consumption may be reduced remarkably. A RGB LED exceeds 100% of color production specifications of National Television System Committee (NTSC) and a more vivid image quality may be provided to a consumer.